Wave translating device



June 29, 1948. R, s, OHL

wAvE TRANSLATING DEVICE Filed July 27, 1945 ATTORNEY .wtionalmewnomar circuiteelementfimcross -fsec- Patented June 29, 1948 .seismic-@E -npplicatiumraiyecz 1945,sseriaihNmlcouizs ilroiaim's. (Cisne- 17125) gill inventionrelates.tofmicrowave-translating papuaratus, fand zilvanticularly, vbo f such iapparatus pxoilided With=.capability for; handling-ea: relatively amountiofr-sisnalinsipower.

.t iftherdevclopmentof signaling systems .Lior `-fnicnarrates havinga-Wavelength;ofntheorderzof lioneimetemoi. lasst one. critical K nieeclwisfa i satisfac- `to,ry,znioelulating device-g for handling; thesalmount fief signaling :power i ,involved fIo be attractive fromxa circuit standpoint, such devic'eishoulldem- 1.0

y"formed -'=With 'itapere'ri f portion. iAvi plurality of c@ asg'ili'dff'zrectiier` elements` is-y mounted irrasteppedifreila-tiomalong therflongitudinalf axis ofsuchfiportion, #anni -'a' `pluralityI fi-leadsi isiconnected-tothe: rectilier, elements and extends across the wavefguide 1j'ftof'eirpose '.-varying lengths Linterioiily` thereof and itodtelfninite outside thereof. Af-'sourcefrbiasing wcitgeiis' connecties-via. tneseueadsfltothefseeti- :Iier elements. A signal source isconnectedincircuit with "theleads an'd biasing source "it-has `j been-*found in practicejthatj thei foregongnlicro- .Wayeetgranslatillg apparatusM embodies. a' substanifiallyincreased ca;.ialiilit',yfon` handling; signal ven- Lefg i i i thefollowing descllptonxtaken:,together -withxthe saecompanyinggdrawing;inpwhieh; 4,

L Fig. 1 is a schematic circuit diagram oiiaimicro tuttavia?itispm'slating'sapparatusffinoluidingf' tembolimentnorthe inuentionfandflshom g Herein, the.. termV Ylrrviicifqvirave denotes a'wave ,having alensth less thanione meter. and ,as short g5 :as one; ceilliimfetertorsonemjllimeter.

'Beierringlto:Fisstli and-2; a source 'lbfzarr irien.microlli/aves is connected :to inner-conductor .1U sandgouter. Y riductorljfbth of whiclifconst ituteaA coaxialgconductorline"9. TAt 'the lefth'a'iidendwoilwaveggliide 113,', the outer'y conductor L2isiectricallmconnected thereto, anjd a` portion t4 ...ofthe tinnertcoriductor l Ircoveeld with dielectric I 'l extends Anto the' interior. ci *wave .guide @1.3-i thougna', suitable.Y opening inflanflipper side Ewall g-theeof. The 'delectricrcoveredportion.. L4` ,-eleetsl. transmission .fbetweenltheoaxial linelS andwaye guide 113 inthe Wellknown man- .:ner. Atltlie'7 righth'and.end..of xwarvenguide f3, @a ,sjmilaiif coaxial -line L. t8 effects ...transmission .bem

$.20 .itween-.WaizetgiiideJ .andfloadf is. A.microwavc ftijansmissionwsystems of .the jforeOirig typ-e', `having a, .suitableziinpedancelmatehdaetweenthe Icar- .riei'ffsouree lltwai/.eguide 1113.211141. load I9 .is ldis- .Ac-losed yin; the conendingmapplicationof W.

#In accordance iwitn. the i present .invention i1- fflustratedcin religies. ;1..and. 2, the. inside.,surface :of 'tlfieuipper sidezoiftwaveguide t3jis formed witna ,constrictedfor.,substantially .Vf-.shaped,L section `25. This comprises liifiearly:` tapered .portions-Scand r2? shaving ypoints of vliiinin-mm l thickness :nearestfstherearrier, source tDma-ndeloaid lil,`4 rezspeeti-ire-lyyfand an intermediate point Hof -maxi zinumthickness. A

5 iMounted; 'nmthectapered-fportionfZ'Ifsinfstepped frlatioxivaglo gv e; longtudinalwa-X-s-of the Wave 3,\1F ifs 1` iandil-e. is'ea; plurality of.; rectifier elements :,218 fwnose partieularfstructune and .-iunotion will .che hereinafterexplained iGen- .A40 f nectedi tofzcaclrrrectiert elementfZ B :is f one 'f endV of .an celectricali iead .229 i vifhielif;i extends ecrlossz ,the iwavc guider! 3 ,"sproject-ing` through: R. 'F.fbyfpass capacitors 30 of well-known strucburein; alower zisidefM-.zwavesguide lvcandfterrninating;atizpoint 3| :dyingy outside: thereof. Theirectie'ruelements::28, t28 :faire:shownfinthe'mumber of ve forgtlierpur -pcs'e l ithisfllustnationsandqsuch 'number @may findividualnflicrowave;systems.

h point 3 i lis .connectedtviazkrleadsSZ,f secondiaryrwindingf'of transformen {33,il`ead.: 34 ian-'dwanf'abiemresistorlf 35 :fito-the 4negative#terlrnin'al..1 of '..a source foibiasing voltage:mhosespositivef'terminalv-.is.=grounlded.\ Q'Alvsource z3 1 :of1 signal )rwaves 55, tisffconnectedlto:the: primary'` winding `of lgtrasns- Rectifier element 28 is shown in Figs. 3 and 4 and comprises a tubular mem-ber 48 of conductive material formed with a thread 4I on its inte- 'rilor surface, each member 48 being mounted in electrical contact with the wave guide I3. At the uppermost end of tubular member 48 is a brass disk 42 provided With a peripheral thread and including a screwdriver slot 43 in its upper surface. Below the disk 42 and protected thereby from damage and/ or dust is a second disk 44 of conduca. tive material formed with a peripheral thread to engage threaid 4I of member 48 and a boss 45 on its lower surface. A Idisk 46 of a suitable seimiconducting material is suitably secured tothe lowermost surface of the boss 45. Such material may include siliconr or germanium or combinations of these elements with slfch other elements as tend to yield improved yelectrical properties. One method of preparing the disk 46 including a polished surface 41 is disclosed in my copending application Serial No. 530,419, filed April 10, 1944, Patent No. 2,437,269.y The disk 44 also embodies a screwdriver slot 43a.

A split ring 48 of tungsten wire is the .polished surface 41 of the'disk 46, and pressed thereon by a flat surface 49 on the upper end of a conductive cylinder '58 having a peripheral thread I and a screwdriver slot 52 in its lower end. A disk 55 of dielectric material embodies a central opening 56 provided with a thread for accommodating the threaded peripheral surface of the cylinder 50, and a peripheral thread for engaging the thread 4I of the member 4I). rA pair of screwdriver slots 51, 51 is formed in the lower surface of the dielectric disk 55. Lead 29 is suitably attached to the lower end of the cylinder 50. The screwdriver slots in the respective components ofr rectifier element 28 serve to adjust their relative positions interiorly of the member 40. For further details on the rectifier element 28 reference is made rto my copending application Serial No. 607,427, filed July 27, 1945.

In the operation of the invention, the variable resistor 35 in Fig. 1 is adjusted and the source 36 is ,poled to apply a preselected magnitude of negative biasing voltage to the split ring 48. The biasing current flows in a circuit including ground connected to the positive terminal of biasing source 36, source 36, resistor 35, lead 34, secondary winding of transformer 33, lead l32, terminals 3l, leads EIL-rectifier elements 28, 28 and wave guide I3 to ground 68 connected to the lower left-hand end. thereof. The energy from signal source 31 is superimposed Via transformer 33 on the biasing current flowing in the circuit just traced. The signal energy varies the eiective resistivity of the combined rectier elements 28, 28 and thereby the effective attenuation thereof. This varies the amount of carrier energy absorbed by the rectiiier elements 28, 28 and as a consequence the 'amount of carrier energy supplied to the load I9.

Thus, the signal energy serves to modulate the carrier energy.

Due to the varying lengths of the leads 29, 29 exposed to the carrier waves in the interior of the wave guide I3, their combined effect tends to simulate the effect of a tapered attenuator Comprising a tapered strip ofcardboard .covered with a film of carbon, and to minimize reflection and thereby maintain the impedance match between the carrier source Ill, wave guide I3, and load I9, hereinbefore mentioned. The modulator com-` prising the constricted section 25, rectifier ele-v ments 218, 28 and leads 29, 29 would be normally located in proximity of the carrier end of wave" positioned on.

guide I3, and because of the foregoing impedance match may be inserted at any suitable point therealong.

The V-shape section 25 in the interior of the wave guide I3 shown in Fig. 1 tends to lower the eiectve .carrier frequency Voltage applied to the' rectifier elements 28, 28.which operate most emciently at low voltages say, for example, of the order of one volt. This is an importan-t consideration in microwave systems transmitting sig-- nal modulated energy at power values up to 30 watts; The rectifier elements 28, 28 have been found to pass 7.5 amperes at approximately one volt and to operate continuously at approximately degrees centigrade with no apparent impairment thereof. Thus, the rectifier elements provide the microwave translating system -with a substantially increased power handling capability. As circumstances warrant, the rectifier elements 28, 28 may be water or forced-air cooled.

The lengths of the leads '29, 29 exposed in the interior of the wave guide I3 should not exceed one-quarter wavelength to provide the system of Fig. 1 with a broad band characteristic from a frequency standpoint say, for example, several hundred megacycles at a wavelength of the order of one centimeter. The over-all spacing of the rectifier elements 28, 28 should probably not exceed one wavelength, nor be less than one-half wavelength.

Although the modulation is eiiected in Fig. l with a negative bias applied to the rectifier element 28, it will be understood that modulation can also be effected with a positive bias applied to the rectifier element 28, in which case the terminals of the biasing source 35 are interchanged.

VWhat is claimed is:

l. In combination, in microwave translating apparatus, a tapered. section of guide for the transmission of microwaves, a plurality of variable impedance elements mounted in stepped relation longitudinally of said section of guide, a plurality of electrical leads for coupling said elements to the transmitted microwaves, each of said leads having one end connected to one of said elements and extending across the interior of said section of guide to project its opposite end outside thereof, said leads being exposed varying amounts in the interior of said section of guide whereby said elements are coupled varying amounts to the transmitted microwaves, and electrical circuit means connected to the ends of said leads outside said section of guide for Varying the impedance of said elements.

. 2. A combination according to claim l in which said elements and associated leads are mounted along the longitudinal axis of said section of guide.

3. Microwave translating apparatus comprising, in combination, a section of guide for the transmission iof microwaves, a plurality of variable impedance elen1ents,'rneansv for individually coupling said elements to the transmitted microwaves in progressively increasing degree atrespectively corresponding sucoe'ssive'points along said section of guide, and electric circuit means for Varying the impedance of said elements concurrently. 'f

4. In combination, a section of guide for the transmission of microwaves, and a plurality of microwave. power absorbers individually coupled to the transmitted microwaves at respective successive points along said section of guide, the coupling of said power absorbers .progressively increasing vfrom one to another thereof@ 5. A combination according to claim 4 in which said section of guide is tapered.

6. A combination according to claim 4 in which said power absorbers comprise variable impedance elements, and which includes electrical circuit means for concurrently varying the impedance of said elements. t

7. A combination according to `claim 4 in which said absorbers are coupled at successive points along the longitudinal axis of said section of guide.

8. A combination according to claim 1 in which said elements are stepped longitudinally of said section of guide an overall distance of at least one-half wavelength.

9. A combination according to claim 1 in which the amounts of Varying exposure of said 15 Number REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date Zworykin June 29, 1937 Southworth et al. Feb. 1, 1938 

